In recent years transcatheter approaches to treat heart valve disease have played an increasingly important role. This has been especially true for aortic stenosis, with two valves commercially available in Europe and several others under investigation in man. These least invasive therapies have expanded treatment options for the highest surgical risk patients, but there are fundamental differences from conventional surgical repair that warrant further investigation. This manuscript reviews the rapidly evolving field of transcatheter aortic valve intervention from the clinician's perspective. Anatomic, pathologic, and physiologic issues posed by the disease process are first reviewed. Device and design challenges to this new therapy are then addressed. Finally, newer devices and transcatheter approaches to other valve disease are briefly reviewed. The understanding that can come from an engineering approach to address these multiple issues should further improve outcomes and advance development of next-generation devices.